Form of tungsten and method of producing the same



Patented July 3, 192%. I

COLIN G. FINK, OF YONKERS, YORK.

FORM OF TUNGSTEN AND METHOD OF PRODUCING THE SAME.

No Drawing.

This invention relates to the production of a tough, flexible, ductiletungsten.

The object of this invention is to produce tungsten of a tough, flexiblecharacter and which may be manipulated with ease, and is not subject tosagging when used as a filament in lamps.

Other objects of the invention will be obvious and will in part ap earhereinafter;

The invention accordingy comprises the several steps and the relationand order of one or more of such steps with respect to each of the'others, and the article possessin the features, properties, and therelation 0 elements, which are exemplified in the following detaileddisclosure, and the scope of.

the application of which will be indicated in the claims.

Heretofore tungsten has been generally regarded as a hard, brittle metalossessing' little or no malleability or ducti ity when cold to theextent that in the process of drawing it into wire, the dies and thewire' are both heated to an elevated temperature. Tungsten hasheretofore been-known, moreover, as possessing the undesirable qualityof losing its stiffness at incandescent temperatures so that when usedas a coil in a lamp there is a tendency of the coil to sag, which mayreach the point of causing adjacent turns to touch causing a shortcircuit.

In accordance with this invention, it has been discovered that whenproduced in accordance' with the process herein outlined, a .new form oftungsten is obtained which is tough and flexible when cold, to theextent that it. can be passed throu h a drawing die Without heating. Ihave ound, moveover, that this new wire is durable and possesses littleor no tendency to sag when used in the filament even though elevated toa. temperature far'in excess of that ordinarily employed in incandescentlamps.

The metallurgy of tungsten has not yet reached the pointwhere the factsare beyond.

question, but when tungsten rods heretofore manufactured fracture,amicroscopic exam- 4 .ination of the fracture reveals the fact that it isa cleavage between crystals while the crystals themselves remainunbroken. The

the resence of small quantities of impurities tween the crystal faces,which impuri- Application filed January 16, 1824 'Serial Ho. 686,628.

ties are of less'tensile strength and present less adhesion to thecrystal faces than the tensile strength of the crystals themselves.These impurities, moreover, are of'a character such that they are notreduced in the hydrogen atmosphere in which the tungsten is treated inany adequate degree, if at all;

In accordance with this invention, these intercrystallineimpurities areeliminated, and to this end there mav be introduced into the process asubstance capable of reducing these impurities to less objectionableform.

The nature or amount of the interfacial or intercrystalline impuritiesspoken of have not yet been ascertained, but in all probability itcomprises an oxide or similar compound of tungsten of such a nature orcharacter-that it cannot be removed by the hydrogen in the treatingbottle. These impuritiesana'y beeliminated by the addition to thetungsten slug of a substance having a high atlinitive for hydrogenwhereby the slug may retain its hydrogen even up to high elevatedtemperatures. Thus, for example I- have found that it 1.4% by weight or'zirconium is added to the slug, the zlrconium, probably because of thefact that it forms a hydride which is not easily dissociable at hightemperatures, is capable of re acting with the intercrystallineimpurities to eliminate them and that when such elimination hasoccurred, an entirely new and radically different form of tungsten isobtained.

I have found that the action maybe very much hastened by insurin thatthe slug shall be in a porous condition while undergoing the treatment.A convenient way of efl'ecting this is by the addition to the slug of asmall proportion of the substance incapable of alloying with tungstenbut which will preferably be completely eliminated by the subsequent'treatment. A suitable ma terial for this purpose is copper.

A practical mannerlof carrying out this invention therefore comprisesthe addition to the tungsten slug of, for example, about 1.4% by weightofzirconium and about 2 or 3% by weight of copper, When such a slug isit is sufficiently ductile so thatit may be It has been found that it isadvantageous to add a small proportion of hydrocarbon vapor to the hydroen in the treating bottle, as for example, y passing the dried hydrogenthrough a mixture of aniline oil and pyridine,'as in this way theresults are attained quickly, accurately and reliably.

This new form of tungsten is radically different from that heretoforeknown. It is sufliciently soft to be cut by a hack sawdrawn throughseveral. passes of wire dies without heating and when broken it give thecharacteristic fibrous structure of metals which break through thecrystals. When concentrated filament lamps are made out of the wire ofthis invention, they have little, if any, tendency to sag even atextreme temperatures.

' Since certain changes in carrying out the above process, and certainmodifications in the article which embody the invention may be madewithout departing from its scope, itvis intended that all matter con-.tained in the above description or shown in .thefaccompanyin-g drawingshall be interpreted as llustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of 'the inven tion hereindescribed, and all statements of the scope of the invention, which, as amatter of'language, might be said to fall therebetween. v I

' Having described my invention, what '1 claim as new and desire tosecure by Letters Patent, is:

1. The process of preparing tungsten bodies containing tungsten crystalsin part, which comprises incorporating in a slug of tungsten material arelatively small amount of a substance having a .high aflinity forhydrogen at relatively elevated temperatures and capable of reactingwith intercyrstalline impurities, and then heat-treating said slug 1nydrogen to roduce the reaction whereb the intercrystal ine impuritiesare remove Q. The process of preparing tungsten bodies containingtungsten crystals in part, which comprises incorporating in a slug oftungsten material, a substance containing zirconium in an amount in theneighborhood of 1.4% by wei ht, and then heat-treating said slug in aydrogen atmosphere at a temperature adapted to produce a reactionwhereby the introduced substance substantially removes allintercrystalline impurities.

3. The process of preparing tungsten bodies containing tungsten crystalsin part, which comprises incorporating in a slug of tungsten material asubstance comprising zirconium taken by weight in an amount of about1.4% and copper taken by wei ht in an amount not in excess of 3%, anthen heat-treating said slug in a hydrogen atmosphere at a temperatureadapted to roduoe a reaction whereby the introduced sdbstancesubstantially removes all intercrystalline im urities.

testimony whereof I aflix m si COLIN ature. NK.

